As well known in the art, a typical vacuum gripper system includes a hollow main body, a pad coupled to a lower portion of the main body so as to communicate therewith, and a vacuum pump connected to a side or upper side of the main body by a hose. When high-speed compressed air passes through the vacuum pump while the pad is in contact with an object, air present in the pad is pulled through the stream of the compressed air into the vacuum pump via the main body and the hose, and is discharged to the outside of the vacuum pump together with the compressed air. Herein, a negative pressure is thus created in the pad and this negative pressure acts to suck and grip the object. Thereafter, the gripped object is transported to a desired location by an automation system or the like.
Such a gripper system is currently used effectively, but is problematic in design, wiring, and the like. Accordingly, a vacuum gripper device having a relatively compact structure by mounting a vacuum pump inside a main body has been proposed. It is noted that Korean Patent Application Publication No. 10-2009-0131617 and U.S. Pat. No. 7,540,309 disclosed vacuum devices regarding said vacuum gripper device.
Referring to FIG. 1, the former vacuum gripper device 1 is configured with a ‘T’ type hollow main body 2, a suction pad 3 coupled to a lower portion thereof, a vacuum pump 4 mounted therein at a first side thereof, and a compressed air supply hole 5 formed therein at a second side thereof. Furthermore, a release valve 6 operated by the pressure of the compressed air is positioned below the compressed air supply hole 5. For reference, the latter device remains substantially the same as the former gripper device 1, except that the release valve 6 is positioned above a ‘+’ type main body and a description there will be omitted herein. In the drawings, reference numeral 7 denotes a silencer.
As in the typical vacuum gripper system described above, when high-speed compressed air passes through the vacuum pump 4 while the suction pad 3 is in contact with an object P, air present in the suction pad 3 is pulled through the stream of the compressed air into the vacuum pump 4 via the main body 2, and is discharged to the outside of the vacuum pump 4 together with the compressed air. Herein, a negative pressure is thus created in the suction pad 3 and this negative pressure acts to suck and grip the object P. Meanwhile, the release valve 6 remains closed by a portion of the supplied compressed air continuously pushing the release valve 6, so that the vacuum inside the vacuum pump 4 can be maintained.
For example, when supply of the compressed air is stopped after transport of the object P, the release valve 6 is caused to be opened by the pressure of a spring acting thereon. Then, external air is permitted to flow into the main body 2 and accordingly the vacuum and the negative pressure in the device are released. The vacuum gripper device 1 is removed from the object P and then prepared for a next gripping process.